Sustaining crop yield and water quality under climate change in intensively managed agricultural watersheds—the need for both adaptive and conservation measures

Abstract

The projected near-future climate (2031-2059) of wetter springs and drier summers may negatively affect agricultural production in the US Midwest, mostly through reduced aeration of the root zone due to excess soil water and frequent loss of nutrients such as nitrate (NO3-N) and total phosphorus. Several agricultural adaptations—such as adding tile drains and increasing fertilizer rates—may be deployed to mitigate potential reductions in crop yield. However, these adaptations (generally driven by economic benefits) may have a severe impact on water quality, which is already under stress due to excess nutrient runoff from agricultural fields causing hypoxia in inland and coastal waters. Here, we evaluate the crop yield and water quality consequences of such adaptations under future climate with the Soil and Water Assessment Tool in a testbed watershed located in central Illinois. We show that additional tile drains and increased fertilizers can help achieve baseline (2003-2018) corn yields but with a nearly two-fold increase in riverine NO3-N yield affecting a major drinking water supply source. However, a shift to spring-only fertilizer application may not require additional fertilizer and reduces the increase in NO3-N loss to 1.25 times above the baseline. We also show that water quality may improve (better than baseline) with conservation measures such as cover crops and switchgrass. Our findings highlight the need to develop efficient climate change adaptation and conservation strategies for sustainable agriculture and water quality.